[Diagnostic usefulness of Ca 19-9 antigen in cancer of the pancreas and neoplasms of the pancreato-biliary intersection].

Antigen CA 19-9 was measured in the serum of a group of 16 patients with pancreatic cancer, in 19 patients with non-pancreatic gastrointestinal malignancies, and in 19 others with benign pancreatobiliary disease. The test showed a high sensitivity with a low specificity and a positive predictive value for diagnosis of pancreatic cancer when confronted with a group of controls that included both benign and malignant gastrointestinal disease. The low specificity was due to high CA 19-9 values in other gastrointestinal cancers, especially in carcinoma of the ampulla and the biliary tract. When the latter were added to the group of patients with pancreatic cancer, and the diagnostic accuracy of the test was re-evaluated, sensitivity, specificity and both positive and negative predictive values increased. Values of CA 19-9 over 100 U/ml are highly predictive of malignancy in patients with pancreato-biliary disease.